Photometric precision of a Si:As impurity band conduction mid-infrared detector and application to transit spectroscopy

Abstract

Transit spectroscopy is the most promising path toward characterizing nearby terrestrial planets at mid-infrared wavelengths in the next 20 years. The Spitzer Space telescope has achieved moderately good mid-infrared photometric precision in observations of transiting planets, but the intrinsic photometric stability of mid-IR detectors themselves has not been reported in the scientific or technical literature. Here, we evaluated the photometric precision of a JWST MIRI prototype mid-infrared Si:As impurity band conduction detector, using time-series data taken under flood illumination. These measurements of photometric precision were conducted over periods of 10 hours, representative of the time required to observe an exoplanet transit. After selecting multiple sub-regions with a size of 10x10 pixels and compensating for a gain change caused by our warm detector control electronics for the selected sub-regions, we found that the photometric precision was limited to 26.3ppm at high co-added signal levels due to a gain variation caused by our warm detector control electronics. The photometric precision was improved up to 12.8ppm after correcting for the gain drift. We also translated the photometric precision to the expected spectro-photometric precision, assuming that an optimized densified pupil spectrograph is used in transit observations. We found that the spectro-photometric precision of an optimized densified pupil spectrograph when used in transit observations is expected to be improved by the square root of the number of pixels per a spectral resolution element. At the high co-added signal levels, the total noise could be reduced down to 7ppm, which was larger by a factor of 1.3 than the ideal performance that was limited by the Poisson noise and readout noise. The systematic noise hidden behind the simulated transit spectroscopy was 1.7ppm.

arXiv comment16 pages, 10 figures and 2 tables, it has been accepted by PASP

References in corpus (16)

• Analytic Lightcurves for Planetary Transit Searches
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• Characterizing transiting exoplanet atmospheres with JWST
• The climate of HD 189733b from fourteen transits and eclipses measured by Spitzer
• 3.6 and 4.5 Micron Phase Curves and Evidence for Non-Equilibrium Chemistry in the Atmosphere of Extrasolar Planet HD 189733b
• Habitable worlds with JWST: transit spectroscopy of the TRAPPIST-1 system?
• The 8 Micron Phase Variation of the Hot Saturn HD 149026b
• Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 Production
• The Mid-Infrared Instrument for the James Webb Space Telescope, VII: The MIRI Detectors
• Repeatability and Accuracy of Exoplanet Eclipse Depths Measured with Post-Cryogenic Spitzer
• The Mid-Infrared Instrument for the James Webb Space Telescope, VIII: The MIRI Focal Plane System
• Telling twins apart: Exo-Earths and Venuses with transit spectroscopy
• A New Concept for Spectro-photometry of Exoplanets with Space-based Telescopes
• Repeatability of Spitzer/IRAC exoplanetary eclipses with Independent Component Analysis
• Pupil Masks for Spectrophotometry of Transiting Exoplanets
• A New Method for Calibration of Gain Variation in Detector System

Cited by in corpus (7)

• JWST Noise Floor I: Random Error Sources in JWST NIRCam Time Series
• The Detectability of Rocky Planet Surface and Atmosphere Composition with JWST: The Case of LHS 3844b
• AU Microscopii in the FUV: Observations in Quiescence, During Flares, and Implications for AU Mic b and c
• Effects of UV stellar spectral uncertainty on the chemistry of terrestrial atmospheres
• A New Method for Finding Nearby White Dwarf Exoplanets and Detecting Biosignatures
• Where are the Water Worlds?: Self-Consistent Models of Water-Rich Exoplanet Atmospheres
• A Disintegrating Rocky World Shrouded in Dust and Gas: Mid-IR Observations of K2-22b using JWST